Prior Art
Passive restraint systems for motor vehicles take many forms--from the air bag, to the motorized two point shoulder system, to the inflatable seat belt. At the present time in two point passive belt installations, a lap belt is recommended which is typically a non-passive component in that the vehicle occupant must put it on.
An example of the motorized two point shoulder system is U.S. Pat. No. 4,313,622 issued to Suzuki et al and entitled "Passive Seat Belt System". In that system, one end of the shoulder belt is moved along a rail in the roof of the vehicle over the door and the other end is fixed at a point at or near the middle of the vehicle. Another example is U.S. Pat. No. 4,354,696 issued to Volk et al. and entitled "Device For Passive Actuation of a Safety Belt".
An example of the inflatable seat belt is U.S. Pat. No. 3,970,329 issued to Lewis and entitled "Inflatable Band Restraint Stitching" which is assigned to a common assignee. In that patent, both a shoulder and a lap belt are provided, but it is not a passive system in that the vehicle occupant must put it on. During a crash situation, the belt inflates in a manner similar to an air bag.
U.S. Pat. No. 4,363,501 issued to Takada and entitled "Passive Type Vehicle Occupant Restraint Belt System" describes an improvement in the reduction device between an electric motor and the transfer wire to move the belt. This patent further illustrates a three point passive system wherein the shoulder belt is fixedly attached to one end thereof to the upper rear corner of the vehicle door, opposite the hinge edge, and at the other end to a door-mounted retractor located at the lower rear corner of the vehicle door. The shoulder belt passes through a D-ring connected to a lap belt and through a moveable slide mounted in a track on the door. As the door is opened, the slide moves from the lower rear corner of the door to a position on the door near the door hinge edge.
Other than the system described in U.S. Pat. No. 4,363,501, at least one part of the system is a non-passive system. In the U.S. Pat. No. 4,363,501, the lap and shoulder belts are passively placed around the occupant, but passenger convenience is missing. The shoulder belt, is in the way when the door is opened for entering or leaving the vehicle. In addition, the racked wire for moving the lap belt must be stored in the door after it passes the motor and be capable of being freely played out.